Rekha Basu: Global warming's costs get harder to deny

Even those who don't believe in global warming are now forced to acknowledge its power. For the first time, it became the decisive issue in a high-profile presidential endorsement.

New York City Mayor Michael Bloomberg endorsed President Barack Obama, saying that Superstorm Sandy had reshaped his thinking about the race and that climate change was the main reason. The mayor, a Republican turned independent, referred to efforts Obama has made to curb greenhouse gases.

In linking the storm's impact to global warming, Bloomberg joined New York Gov. Andrew Cuomo, who said earlier, "Anyone who says that there's not a dramatic change in weather patterns I think is denying reality."

The devastation hit some 19 states, causing homes to collapse, 8.5 million people to lose power, and more than 100 people to die. It brought storm surges of an unprecedented 14 feet.

But some conservative websites pounced on the idea of a link to global warming. "Famed climatologists Mike Bloomberg and Andrew Cuomo blame Sandy on climate change," scoffed one. Fox News offered the headline "Scientists dispute politicians' claims that global warming grew Sandy," while linking to a New York Times blog post that's far more nuanced.

Here's how the president-elect of the American Meteorological Society, J. Marshall Shepherd, explains such denials. Quoting author Upton Sinclair, Shepherd told New York blogger Kevin Powell:

"'It is difficult to get a man to understand something when his salary depends on him not understanding it.' There are sectors of our society that have a vested interest in creating confusion and misinformation on the topic, even as the overwhelming majority of scientists and published literature are clear."

So what is the superstorm's connection to global warming? I write this, at the risk of being mocked as another "noted climatologist," because like many other nonscientists I've been struggling to understand the recent spate of severe storms, tsunamis, tornadoes, hurricanes and cyclones, and the warm winters, dry springs and other sometimes-cataclysmic weather anomalies.

To synthesize what I've learned:

Hurricanes, tornadoes and other storms are caused by changes in heat and water evaporation. Scientists believe that as air and sea temperatures rise, hurricanes will be stronger and wetter. That's because water expands with heating, oceans absorb more heat than land does, and warmer air can hold more moisture.

Melting glaciers also add to rising sea levels. The temperature in the western Atlantic Ocean reportedly is 5 degrees above normal for this time of year.

Frances Beinecke, president of the Natural Resources Defense Council, blames climate change for "swelling our seas, so that storm surges are higher and cause more flooding." In a blog she wrote, "From Norfolk, Va., to Boston, sea levels are rising four times as fast as the global average. Hurricane Sandy cut right along those swollen seas."

Though climate changes occur naturally, the pace has been accelerating so transformations that took tens or hundreds of thousands of years now happen over decades.

That's because of increased greenhouse gases from the release of carbon dioxide, methane, nitrous oxide and chlorofluorocarbons. They result from burning coal and gasoline, cutting down rain forests that act as shields, and dumping methane gases from animal waste (such as hog confinements) into the environment.

That's 90 million tons of global-warming pollution every day, according to former Vice President Al Gore.

Shepherd calls on the public to press policymakers for solutions, such as cap and trade, carbon taxes and carbon capture. Bloomberg praised Obama for, among other things, pushing for regulations to curb emissions from cars and power plants.

Most Americans now believe in global warming. While deniers may have a vested interest in cutting back on fossil fuels, even leaders who court business and industry should consider the financial costs. The damage from Sandy is now expected to reach $50 billion.

Two former Republican presidential candidates, Jon Huntsman and Tim Pawlenty, voiced a belief in global warming. Neither got the nomination.

Mitt Romney, on the other hand, used global warming as a joke in his acceptance speech. "President Obama promised to slow the rise of the oceans and to heal the planet," he scoffed. "My promise is to help you and your family."

As we're seeing, rising oceans can also have a terrible impact on people and families. And possibly even politics.